In the machining of workpieces, it is necessary to fasten the workpiece securely to the table of the machine tool. The invention is specifically directed to a clamp for a machine tool table provided with an inverted T-shaped slot opening onto the upper surface of a work table. In the past, various types of clamps have been used with this type of machine tool table. The prior art clamps have usually consisted of a bolt whose head is T-shaped and which is slidable in a T-shaped slot in the machine tool table. The bolt extends upwardly from the table, passes through a clamping element, and a large nut is threadingly mounted on its upper end. The clamping element includes an elongated portion which extends horizontally from the bolt and rests on the upper portion of the workpiece. The bottom of the workpiece rests directly on the upper surface of the work table. The workpiece is clamped tightly in place by rotating the nut at the top of the bolt. The thread provides all the vertical support for the clamp and the clamping axis is spaced from the bolt axis, thereby producing a moment arm acting to distort the bolt and creates a considerable amount of compressive force on the limited number of threads which are engaged by the nut in a particular clamping position. These and other difficulties experienced with the prior art clamps have been obviated in a novel manner by the present invention.
It is, therefore, an outstanding object of the invention to provide a workpiece clamp comprising two telescoping pieces, one of which provides all of the vertical support for the clamp.
Another object of the present invention is the provision of a workpiece clamp design which is strong, durable, and not affected by the various forces involved in clamping a workpiece.
A further object of the instant invention is the provision of a workpiece clamp which is adjustable for clamping a wide size range of workpieces.
It is another object of the instant invention to provide a workpiece clamp in which the main body is provided with two clamping elements which are selectively utilized to clamp workpieces within different size ranges.
A still further object of the invention is the provision of a workpiece clamp comprising two telescoping elements, including means for adjustably locking one element in a wide range of vertical positions relative to the other element and wherein the clamping element is adjustably mounted with respect to one of the portions.
It is a further object of the invention to provide a workpiece clamp which is simple in construction, easy and inexpensive to manufacture, and is capable of a long life of useful service with a minimum of maintenance.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.